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Differences in time from HIV seroconversion to CD4+ lymphocyte end-points and AIDS in cohorts of homosexual men
P J Veugelers1, M T Schechter, B Tindall
1Municipal Health Service, Department of Public Health, Amsterdam, The Netherlands.
Insights
Laboratory variations significantly impact CD4+ count decline in homosexual men, affecting HIV progression studies. Consistent CD4+ measurement calibration is crucial for accurate AIDS incidence tracking.
Area of Science:
- Immunology
- Epidemiology
- Virology
Background:
- CD4+ T-cell counts are critical biomarkers for HIV/AIDS progression.
- Assessing CD4+ decline and AIDS incidence across cohorts is vital for understanding HIV natural history.
- Laboratory variability in CD4+ measurements can complicate cohort comparisons.
Purpose of the Study:
- To evaluate CD4+ count decline in relation to AIDS incidence among homosexual men.
- To quantify the impact of laboratory variation on CD4+ measurements.
- To assess the influence of different AIDS case definitions on HIV epidemic studies.
Main Methods:
- Analysis of 403 homosexual men from five cohort studies with documented HIV seroconversion dates.
- Kaplan-Meier survival analyses to evaluate time to CD4+ count < 500 or 200 cells/μL and AIDS diagnosis.
- Comparison of CD4+ depletion rates and AIDS incidence across different cohorts.
Main Results:
- Significant differences observed in CD4+ depletion rates among cohorts.
- No significant differences found in AIDS incidence based on the 1987 definition.
- CD4+ depletion variability is primarily attributed to laboratory measurement differences.
Conclusions:
- Laboratory variations significantly influence observed CD4+ depletion rates.
- Calibration of CD4+ measurements is necessary for reliable policy recommendations.
- The 1993 AIDS case definition alters incubation time, complicating natural history and epidemic trend studies.
Objective:
To evaluate the decline in CD4+ counts in relation to the incidence of AIDS in different cohorts of homosexual men and to quantify possible consequences of laboratory variation in CD4+ measurement.
Methods:
Our study includes 403 men with well documented dates of HIV seroconversion originating from five cohort studies among homosexual men. Differences in time from HIV seroconversion to the first CD4+ count dropping < 500 or 200 x 10(6)/l and to AIDS were evaluated using Kaplan-Meier survival analyses.
Results:
We found considerable differences between cohorts in CD4+ depletion, but not in the incidence of AIDS (1987 definition).
Conclusions:
Variation in CD4+ depletion appears to be mainly the result of laboratory differences. Policy recommendations on a basis of CD4+ counts probably requires a calibration of measurement. The 1993 AIDS case definition leads to a site-specific shortening of the incubation time, which complicates the study of the natural history of HIV infection and of trends in the AIDS epidemic.